Thermal controls for engine cooling systems



April 10, 1956 D. WATKINS THERMAL CONTROLS FOR ENGINE COOLING SYSTEMS Filed Jan. 10, 1955 INVENTOR. 40cm: 0. WQTK/Nfi A T'TORNE V5 United States PatcntO.

THERMAL CONTROLS FOR ENGINE COOLING SYSTEMS Lucius D. Watkins, Hartland, Wis., assignor to Outboard, Marine '85 Manufacturing Company, Waukegan, III., a corporation of Delaware Application January 10, 1955, Serial No. 480,753

11 Claims. (Cl. 123-4138) This invention relates to thermal controls for engine cooling systems, particularly for the initially drained cooling systems of engines of outboard motors.

The purpose of this invention is to provide a thermostatic control which, with the engine cool, will permit the empty cooling jacket to fill with water, and which will thereafter control the flow of water into the block according to water temperature, the control being independent of pressure and effected without altering pump operation.

These results are secured by providing a coolant bypass in parallel with the cooling jacket and by locating the control valve where it is subject in all positions to substantially equalized pressures on its opposite faces.

The drawing is a schematic view partially in elevation and partly in cross section of the cylinders and cooling jacket of an outboard motor engine.

The invention is applicable to any engine, compressor, or the like and is illustrated for purposes of exemplification, as applied to an outboard motor engine, where it has specific advantages.

The drawing shows an engine having the customary cylinders surrounded by jacket 11 having restricted communication through cylinder head gasket 12 with the cylinder head coolant passage 13. Coolant supplied by the pump 30, as from the body of Water in which the outboard motor operates, is delivered through passage 14 and by-pass chamber 15 into the head passage 13. The by-pass chamber 15 communicates through port 16 with outlet conduit 17 and is controlled by thermostatically operable valve 18.

When the engine jacket 11 is full, coolant flows through jacket 11 and overflows through outlet port 19 into return passage 20, through which all water from the cooling jacket flows. Passage 20 leads via port 22 into outlet tube 17, through which coolant returns to the coolant source. In the case of an outboard motor, this would be the body of water on which the boat is floating. Valve 18 floats" between ports 16 and 22 to vary relative flow to the discharge pipe 17.

Bimetallic strip 23 has a hole 24 near the upper end, which hole is of greater diameter than screw 25. To prevent electrolytic action, the gaskets 26 may desirably be of electrically non-conductive material. They are positioned at opposite sides of strip 23 so that when the strip is mounted to outside wall 27 by screw it is electrically insulated from the screw as well as from the wall.

Alfixed in any suitable manner to the lower end of bimetallic strip 23 is a valve stem rod 28 extending through port 22 into the upper portion of outlet tube 17. Valve member 18 is mounted on rod 28 between port 16 and port 22, in such a position that upon axial movement of rod 28 caused by bending of bimetallic strip 23, valve member 18 will vary the relative volume of water admitted to outlet tube 17 from port 16 as compared to that admitted from port 22. Either of ports 16 and 22 2,741,231 Patented Apr. 10, 1956 may be completely closed by an extreme movement of valve member 18. Since both ports are alike subject to pump pressure, the pressures on the valve are substantially balanced at all times when the system is full of coolant.

In operation, water driven by pump 30 enters the inlet tube 14. It may follow either or both of two paths, depending on the position of valve 18. One path is through by-pass chamber 15 into the water jacket passages 13, 1 and returning through passage 20 and port 22 to the water exhaust tube 17. The other path is through the by-pass port 16 past the valve member 18, directly to the water exhaust tube 17.

In the case of an outboard motor engine, the cooling jacket 11 and 13 may be empty when the engine is started due to gravity discharge during the period the pump 30 was not in operation. The lay-pass port 16 is substantially fully open and port 22 is substantially fully closed when the engine is cold. The pump 13 will then direct the major portion of the water through the bypass port 16, since gravity will tend to resist any flow of water upwardly in the jacket 13. Since the cooling jacket is empty, engine heat rapidly warms the thermostatic element 23 and the valve member 18 is moved toward the bypass port 16, overcoming the head of pump pressure and diverting the flow of water through port 15 into the jacket 13. As soon as the thermostatic element 23 becomes immersed in water returning through passage 20 from the water jacket, and its temperature is modified thereby, valve member 18 moves toward port 22 and enough water is allowed to by-pass the jacket 11 and passage 20 to maintain the water therein at the proper temperature. In normal operation, the valve will tend to "float" between the ports which it controls and approximately in the mid-position in which it is illustrated.

Ports 16, 29 and 22 are substantially the same size and are subject to substantially the same water pressure after the jacket is filled. Also, the stream of water from tube 14 is directed to substantially bisect the angle between port 16 and port 29. Therefore, valve member 18 is not urged in either direction by water pressure during normal operation, nor is it subject to variations in operation due to variations in water pressure, since the pressure on both sides is substantially equal.

It will be understood that the thermostatic element might be of a different type and could be positioned differently and connected differently to the valve without departing from the spirit of this invention. The arrangement disclosed has the advantage of great simplicity and effectiveness. It substantially balances water pressures upon opposite sides of the valve, leaving the valve free to respond readily to relatively light thermostat pressure.

I claim:

I. In an internal combustion engine having a cooling jacket, a pump for coolant, a coolant intake duct from said pump to said cooling jacket, and a return passage opening from the jacket; the combination of means providing an outlet duct and having ports respectively leading from the intake passage and the return passage to the outlet duct, and apportioning valve means positioned at said ports for opening either and simultaneously restricting the other to control the relative flow of water through the ports, and an actuating element connected to said valve means.

2. The device of claim 1 in which said actuating element is a thermostat.

3. The device of claim 1 in which said ports are opposed and said valve means is a single valve disposed between the ports for approach toward one and from the other as impelled by said element.

4. The device of claim 3 in which the connection of the element to the valve means comprises a stem disposed for reciprocating axial movement through the port leading from the return passage to the outlet duct, said actuating element comprising a thermostat exposed to the heat of coolant in said return passage.

5. The device of claim 4 in which said element comprises a bimetallic strip mounted in said return passage.

6. In an outboard motor having a cooling system including an inlet passage and an outlet passage and an intervening jacket connected in series between said passages, the improvement which comprises means providing a by-pass passage from the intake passage to the outlet passage, the outlet passage having admission ports communicating respectively with the jacket and the by-pass passage, and valve means movable oppositely to and from the respective ports for the progressive opening of one and the closing of the other according to the direction of movement of said means, and a thermostat exposed to jacket temperatures and connected with said valve means for effecting movement thereof in a direction to close the by-pass port and open the port from the jacket to the outlet passage as the thermostat responds to an increase in temperature.

7. The device of claim 6 in which the ports opening into the outlet passage are directly opposite, the valve means comprising a single valve normally disposed in the outlet passage between said ports and having a stem extending through one of said ports to said thermostat.

8. The device of claim 6 in which the thermostat is exposed to jacket heat and adapted, even in the absence of coolant in the cooling system, to receive radiant heat from the jacket and thereby to move valve means toward the by-pass port and away from the port opening from the jacket into the outlet passage.

9. An internal combustion engine having cylinder means and a jacket, means providing a coolant intake passage leading to a lower portion of the jacket, means providing an outlet passage in proximity to the intake passage and having two inlet ports, return passage means extending from an upper portion of the jacket externally oi the jacket proper to one port of the outlet passage, means providing a by-pass from the inlet passage to the other port of the outlet passage, a thermostat in said return passage means, and valve means in the return passage movable oppositely respecting the said ports and connected with the thermostat through said one port.

.8. the device of claim 9 in which the thermostat is disposed opposite the cylinder head to receive radiant heat whether or not the return passage means contains coolant.

ll. The device of claim 9 in which the thermostat comprises a bimetallic element disposed in the return passage means and extending transversely across the cylinder head and having a mounting including electrical insulation isolating the thermostat element.

References Cited in the file of this patent UNITED STATES PATENTS 

